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package com.dalsemi.onewire.utils;

/**
 * Utilities for bit operations on an array.
 *
 * @version    0.00, 27 August 2000
 * @author     DS
 */
public class Bit
{

   /**
    * Write the bit state in a byte array.
    *
    * @param state new state of the bit 1, 0
    * @param index bit index into byte array
    * @param offset byte offset into byte array to start
    * @param buf byte array to manipulate
    */
   public static void arrayWriteBit (int state, int index, int offset,
                                     byte[] buf)
   {
      int nbyt = (index >>> 3);
      int nbit = index - (nbyt << 3);

      if (state == 1)
         buf [nbyt + offset] |= (0x01 << nbit);
      else
         buf [nbyt + offset] &= ~(0x01 << nbit);
   }

   /**
    * Read a bit state in a byte array.
    *
    * @param index bit index into byte array
    * @param offset byte offset into byte array to start
    * @param buf byte array to read from
    *
    * @return bit state 1 or 0
    */
   public static int arrayReadBit (int index, int offset, byte[] buf)
   {
      int nbyt = (index >>> 3);
      int nbit = index - (nbyt << 3);

      return ((buf [nbyt + offset] >>> nbit) & 0x01);
   }
}
